Flash lamp



NOV- 30, 1943- L.. F. ANDERSON 2,335,724

FLASH LAMP I Filed Dec. 3, 1958 ffy-2- ATTORNEY Patented Nov. 30, 1943 FLASH LAMP Lester F.

to Wabash Anderson. East Orange, N. J., assignor Appliance Corporation, Brooklyn,

N. Y., a corporation oi' New York Application December 3, 1938, Serial No. 243,727

1 Claim.

This invention relates to new and useful improvements in ilash lamps such as are used in photography.

The object of the present invention is to provide a lamp particularly suited for taking photographs with cameras having focal plane shutters. Flash lamps of the prior art, depending whether they were lled with foil or wire, had a more or less highly peaked flash characteristic, and the duration of this ilash above the level of photographic effectiveness was not wide enough to obtain complete exposure during the one-fifteenth to one-twentieth of a second timing of the shutter. Attempts to secure this condition by slowing down the burning time o! the material in the flash lamp bulb, would unfavorably react on the proper timing of the ilash lamp with the shutter.

In accordance with the present invention a plateau type of ignition curve is insured for the flash lamp. 'This is accomplished by placing the igniting wire well out of the center of the mass of combustible material, the ignition of which supplies the required flash ignition. The time required for igniting is further prolonged by propagating the flash from the priming material predominantly in the directions away from the larger mass of combustible material.

In order more clearly to illustrate I have shown in Fig. l in side elevation lampembodying my invention, and in- Flg. 2 curves comparing the functioning of my lamp with those of the prior art.

As shown in Fig. 1, a. glass lamp bulb l contains a mass of combustible material,.preferably the invention a ilash below the center of the mass of combustible material 2 near the neck portion of the bulb. This relationship is enhanced by compacting the material near the periphery of the spherical portion of the bulb and packing it more loosely in the center of the spherical portion.

The usual primer paste consisting of a mixture of mutually reactive elements or compounds applied to the .wire 3 and the supporting ends of the leads by dipping it in the paste before assembly. When assembled in the lamp the paste will collect in a bead on top of the wire 3 and near the tops oi the leads l. The lower portion of this primer paste will not harden to the same extent as the upper portion, and ignition will spread more rapidly downwards (in the direction of the stem) then upwards.

Lamps constructed as illustrated in Fig. 1 have a characteristic curve like I0 shown in Fig. 2. The width of the plateau of this curve is' about milliseconds and reaches lVz and 2 million lumens. Curve Il illustrates the usual foil type ash lamp which, while it reaches over 5 million lumens is very narrow. 12 illustrates the usual wlre-nlled ash lamp which is flatter than Il but the width of which is insufficient. The irregularities in the top ci the curve Ill arecaused by the density of the illling.

What is claimed is:

In a :lash lamp a glass bulb closed to the atmosphere and having a spherical portion, combustible wire distributed with substantially uniform looseness throughout the spherical portion except near the periphery where it is relatively compacted, and ignlting means in the bulb near the periphery of the sphere embedded inthe wire ililing but out of the center of the mass of wire.

' LESTER F. ANDERSON. 

